John is leaving for a two week vacation, and emails his 15 year-old neighbor Robert that John will pay Robert $100 if Robert collects his mail and waters his yard while he is away.Robert does not respond, but collects John's mail and waters John's yard while John is away.Which of the following is applicable to a claim by Robert to collect the $100?

A)Robert cannot collect because he never communicated acceptance of the offer.

B)Robert cannot collect because this type of agreement must be in writing.

C)Robert cannot collect because he is a minor who lacks legal capacity.

D)Robert can collect because he performed in accordance with the offer.