My normal advice for task 1 introductions is to write one sentence that paraphrases the question statement. However, there's nothing wrong with writing a two-sentence introduction if there's a lot of different information to introduce.
Last week's question contains a lot of information, so I found it easier to write a two-sentence introduction.
Here's the question statement again:
The bar chart below shows the proportions of English men and women of different ages who were living alone in 2011. The pie chart compares the numbers of bedrooms in these one-person households.
And here's my introduction:
The two charts give information about single-occupant households in England in the year 2011. The bar chart compares figures for occupants' age and gender, and the pie chart shows data about the number of bedrooms in these homes.