问题如下：
Aline Nuñes, a junior analyst, works in the derivatives research division of an international securities firm. Nuñes’s supervisor, Cátia Pereira, asks her to conduct an analysis of various option trading strategies relating to shares of three companies: IZD, QWY, and XDF. On 1 February, Nuñes gathers selected option premium data on the companies, presented in Exhibit 1.
Nuñes considers two option strategies relating to XDF:
Strategy 7: Writing both the April €75.00 strike call option and the April €75.00 strike put option on XDF
Strategy 8: Writing the February €80.00 strike call option and buying the December €80.00 strike call option on XDF
Based on Exhibit 1, the best explanation for Nuñes to implement Strategy 8 would be that, between the February and December expiration dates, she expects the share price of XDF to:
选项：
A.decrease.
B.remain unchanged.
C.increase.
解释：
C is correct.
Nuñes would implement Strategy 8, which is a long calendar spread, if she expects the XDF share price to increase between the February and December expiration dates. This strategy provides a benefit from the February short call premium to partially offset the cost of the December long call option. Nuñes likely expects the XDF share price to remain relatively flat between the current price €74.98 and €80 until the February call option expires, after which time she expects the share price to increase above €80. If such expectations come to fruition, the February call would expire worthless and Nuñes would realize gains on the December call option.
和老师请教一下：
一般说到option，比如说我long一个call，默认行权日期是什么时候呢？
如果我现在long call，是不是默认行权日在未来，然后现在到未来期间股价涨了我就有收益？
而这个日历option，如题说的2月一个call，默认就是2月行权，也就是2月以前股价变化影响现在的收益？
