You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

Question: 23, 18, 16, 11, 9, 4 ?

 Option A: 3

 Option B: 2

 Option C: 7

 Option D: 5

 Option E: 1
Option B

Question: Sum of 19 odd numbers is?

 Option A: 341

 Option B: 351

 Option C: 361

 Option D: 371

 Option E: 381
Option C

Question: what is the speed of a stream if a canoes rows upstream at 8km/hr and downstream at 10.5km/hr.

 Option A: 1.5 kmph

 Option B: 1.25 kmph

 Option C: 1.35 kmph

 Option D: 1.27 kmph

 Option E: 1.22 kmph

Option B