A package of 8 greeting cards comes with 10 envelopes. Kirra has 7 cards but no envelopes. What is the smallest number of packages that Kirra needs to buy to have more envelopes than cards?
(A) 3
(B) 4
(C) 5
(D) 6
(E) 7
Each package of greeting cards comes with $10-8=2$ more envelopes than cards.

Thus, 3 packages of greeting cards comes with $3 \times 2=6$ more envelopes than cards, and 4 packages of greeting cards comes with $4 \times 2=8$ more envelopes than cards.

Kirra began with 7 cards and no envelopes.

To have more envelopes than cards, Kirra must buy enough packages to make up the difference between the number of cards and the number of envelopes (which is 7).

Thus, the smallest number of packages that Kirra must buy is 4 .

Note: We can check that if Kirra buys 3 packages she has $3 \times 8+7=31$ cards and $3 \times 10=30$ envelopes, and thus fewer envelopes than cards. However, if she buys 4 packages, she has $4 \times 8+7=39$ cards and $4 \times 10=40$ envelopes, and thus more envelopes than cards, as required.

ANswer: (B)