Mark wants to know how many families in his neighborhood plan to attend the neighborhood party. he puts all 80 of the neighborhood addresses in a hat and draws a random sample of 20 addresses. he then asks those families if they plan to attend the party. he finds that 20% of the families plan to attend the party. he claims that 20% of the neighborhood families would be expected to attend the party. is this a valid inference?

a. no, this is not a valid inference because he asked only 20 families
b. no, this is not a valid inference because he did not take a random sample of the neighborhood
c. yes, this is a valid inference because he took a random sample of the neighborhood
d. yes, this is a valid inference because the 29 families speak for the whole neighborhood