a$.$ Relative Level of Risk of Principal$-$Agent Problems:

Company A:

Company A has a dispersed ownership structure due to its large number of shareholders and a substantial position owned by a foreign institutional investor $(20\%).$ Dispersed ownership arrangements frequently result in increased principal$-$agent difficulties as a consequence of the division between ownership and control. Minority shareholders may encounter difficulties in overseeing managerial activities, hence heightening the likelihood of conflicts of interest.

Company B:

Company B is overseen by a family that possesses $60\%$ of the outstanding shares, denoting a concentrated ownership arrangement. Highly consolidated ownership arrangements, particularly when under the management of a family, might potentially mitigate issues related to the separation of ownership and control. The family's significant ownership share links its interests closely with those of the corporation, potentially reducing conflicts of interest.

b$.$ Drawbacks Associated with the Ownership Structure of Company B:

$1.$Insufficient Diversification: The family's substantial $60\%$ ownership links their wealth directly to the company's performance, resulting in a lack of diversification. This might subject them to substantial financial vulnerability in the event that the firm encounters difficulties.

$2.$Potential for Entrenchment: Concentrated ownership has the capacity to result in entrenchment, a situation in which the family's influence deters external input or challenges. This may impede innovation and impede the adoption of innovative management methods.

$3.$Restricted Market for Shares: Due to the family's controlling interest, the availability of Company B$\text{'}$s shares on the market may be limited$.$ This might impact the liquidity of the investment, hence posing difficulties for other investors in executing transactions to acquire or sell shares with ease.

$4.$Obstacles in Succession Planning:

Family$-$controlled enterprises frequently face challenges when it comes to succession planning. Lack of a definite strategy might engender ambiguities regarding the management and prospective trajectory of the organisation.