BIG Corporation owns a $75\%$ share of Small Corporation, an $85\%$ share of Little Corporation, and a $90\%$ share of Mini$-$Corp. BIG Corporation plans to install a defined benefit plan for its eligible employees. Which of the following statements apply to the plan that BIG installs?

$....$ I. The plan can be provided to eligible employees of BIG Corporation only.

$....$ II$.$ The plan that is provided to eligible employees of BIG Corporation must also be provided to eligible employees of Small Corporation.

$....$ III. The plan that is provided to eligible employees of BIG Corporation must also be provided to eligible employees of Little Corporation.

$....$ IV$.$ The plan that is provided to eligible employees of BIG Corporation must also be provided to eligible employees of Mini$-$Corp.

Select one:

a$.$

I only

b$.$

II and III only

c$.$

III and IV only

d$.$

II$,$ III, and IV only