Ashish leaves his house at $20 \text{ minutes}$ to seven in the morning,reaches Kunal's house in $25 \text{ minutes}$,they finish their breakfast in another $15 \text{ minutes}$ and leave for their office which takes another $35 \text{ minutes}$. At what time do they leave Kunal's house to reach their office?

• A
  $7:40 \text{ a.m.}$
• B
  $7:20 \text{ a.m.}$
• C
  $7:45 \text{ a.m.}$
• D
  $8:55 \text{ a.m.}$