In a high school, a class teacher is scheduling the six subjects into periods $1$ through $6$ for her class. The subjects are: Hindi, English, Mathematics, Science, History and Geography. She has to abide by the following conditions:
- History has to be immediately after Geography
- Science has to be earlier than History
- English has to be earlier than Mathematics
- English has to be either immediately before or immediately after Hindi
If the Mathematics period is scheduled before Science, then Geography must be which period?
- second
- fourth
- third
- fifth