Explanation
T-bill futures 'discount' can be converted to a price for the bill using the formula Price = [1 - discount * number of days/360]. In this case, this works out to (1- 10% *90/360) * 100 = $97.50. Choice 'd' is the correct answer.

Explanation
The modified duration of a perpetual bond is given by 1/i, where i is the yield. Since I is a positive number greater than zero, it means the modified duration of a perpetual bond is not infinity. Also note that this formula makes no reference to the coupon rate at all - in other words, the modified duration of a perpetual bond is independent of the coupon. The Macaulay duration of a perpetual bond is given by (1+i)/i, again a formula devoid of any references to the coupon. The price of a perpetual bond can be calculated as Coupon/i, which means that a 15% coupon perpetual bond will be priced at exactly 3x the price of a 5% coupon bond.
Based on the above, statement I is incorrect, but statement II is correct. Statement III is incorrect because Bond A will be priced at exactly 1/3rd the price of Bond B, and not less than that. Similarly, statement IV is incorrect as well.
Intuitively, a perpetual bond is nothing but a perpetual annuity, which will have a present value equal to 1/i * cash flow (which in this case is the coupon). The coupon rate only sets the cash flow dollar amount - there is really no difference between the two bonds described in the question except that buying one of Bond B is economically identical to buying three of Bond A.

Explanation
When rates are continuously compounded, we can calculate the marginal rate for year 5 as (5*5% - 4*4%) =
9%. (Note that things would be different if the rates were not continuously compounded, and they were annually compounded. In that case we would need to do a calculation of (1.05^5 / 1.04^4) - 1)